Processes for the production of carbon monoxide and hydrogen from methane or the like



'tion. and carbon dioxide in the combustion gases, the iron 2,773,756 Patented Dec. 11, 1956 ice PROCESSES FOR THE PRODUCTION OF CARION MONOXIDE AND HYDROGEN FROM ME'I'HANE OR THE LIKE Heinrich Met-tel. Enen. Germany,

to It Is Company.

Pm, a corporation I No Dra Application December 31' 1952,

m Sella] m. 329,142

7 Claims. (Cl. lS-ID) r,hyrnelse This invention relates to a conversion of methane. gases containing methane, or gas mixtures containing similar hydrocarbons, into gases containing carbon monoxide and hydrogen, by means of oxygen or air of increased oxygen content, and more particularly to the conversion of such gases with iron catalysts.

It has been found that methane or gases containing methane can be converted into gases which contain carbon monoxide and hydrogen by llrst of all reacting the methane with air in the presence of a combustion catalyst with partial combustion of the methane. whereupon the resulting gas mixture is brought into contact with an iron catalyst in the presence of which the unconverted methane reacts with the reaction products CO: and H20 of the first reaction stage.

However. it has been discovered that difllculties arise with this method of operation it the oxygen content of 'the air is increased or it pure oxygen is used. as is necessury tor example to produce reaction gases ol losv nitrogen content. It the methane gas is reacted with oxygen or air of increased oxygen content in the manner de scribed. the iron catalyst is inactive or inclfective. it has been found that this inactivity or lnetlectivenesa ol' the iron catalyst is due to the composition of the combustion products when oxygen or oxygen-enriched air is used in the combustion step. when oxygen or cameo-enriched 'ltll is used. the combustion products contain higher concentratrons of steam and carbon diootide than is the case when air or normal oxygen content is used for combus- As a result of the increased concentration of steam catalyst is oxidized and loses its activity or el'lectlveness.

Attempts to prevent the reaction of the steam and the carbon dioxide with the iron catalyst by reducing the reaction temperature or reducing it to a harmless value had a negative result. It was found that even below 650 C. an oxidation of the iron catalyst takes place vthrlst at temperatures around 450 C. disadvantageous side reactions predominate.

According to the invention. the products of the combustion. prior to contact with the iron catalyst. are admixed with a sulllcient amount of syntheses gas to produce a gaseous mixture in which the partial pressure of the steam and carbon dioxide are reduced to substantially the value which obtains when the combustion products are the result of combustion with air of normal oxygen content. By to reducing the partial pressures of the steam and carbon dioxide. operation of the process proceetls smoothly and the life of the iron catalyst even after continuous operation over prolonged periods using oxygen or oxygen-enriched air is practically the same as when air of normal oxygen content is used.

Before addition of the synthesis to the combustion products, any water or sleam present therein may be separated in a suitable manner. for example. by impact separators or by condensation. In some cases it is prelerable also to remove in a suitable manner from the rac 2 tion gas the carbon dioxide. for example by washing with water or alkali.

A turther advantage of the process according to the invention consists in that in some cases there may be added to the methane gas before the said partial combustion with oxygen. a certain quantity ol steam in order tor example to control the explosion limit of the methane gas-oxygen mixture without impeding'by this addition of steam the reaction on the iron catalyst.

Example of operation In order hourly to convert 1 N m. of methane into cracking gas in accordance with the equation there are arranged spaced from each other in a vertical reaction tube 540 cut. of nickel catalyst on a magnesite base and 2l60 cm. of fused iron contact. The total catalyst volume of 2.7 litres is charged hourly with 1000 litres of methane and 620 litres of oxygen, corresponding to a volumetric speed of 600.

To begin the operation the cone of the nickel catalyst is lint of all treated in an oxygen-free atmosphere to 6S0-700C. The CHt-Os mixture is then slowly turned on wherealter the combustion of the methane takes place with a light red glow. To the gas there is then added an adjustable quantity of synthesis gas from which steam and it required carbon dioxide have been separated. and the temperature or the iron catalyst is increased to 740-760 C. For the working temperatures stated a space speed of the returned synthesis gas of 1250 volumes of gas per volume of catalyst per hour is suitable in order to protect the iron catalyst from oxidation. With a charge of 2160 cm. of fused iron contact, 2700 litres of synthesis gas were circulated per hour. The total charge to the iron catalyst amounted with the stated operating conditions to about 2000 litres per litre oi catalyst per hour.

From I000 litres of methane and 620 litres of oxygen 2190 litres of synthesis gas are formed showing the ollowing composition:

Coal-6.9 5

CO- 28.4% l==$5.1% Cris-8.6% Nl=0.9%

Rust formation and oxidation are not perceptible.

I claim:

l. A catalytic process [or the production at synthesis gas containing carbon monoxide and hydrogen of high purity and of a relatively low nitrogen content without substantially impairing the activity of an iron conversion catalyst employed in the process. which comprises subiccting to partial combustion a mixture at a normally gaseous hydrocarbon and a gas selected from the group consitting of oxygen and oxygen-enriched air. the oxygen being present in an amount insufiicient to react completely with said hydrocarbon. to thereby form a gaseous product of partial combustion comprising carbon monoxide, carbon dixoide. steam, and unreacted normally gaseous hydrocarbon. admixing said gaseous product with an amount of synthesis gas containing carbon monoxide and hydrogen sullicient to produce a gaseous mixture in which the partial pressure of the steam and the partial pressure of the carbon dioxide are reduced to substantially the value which would be obtained it the gaseous product of partial combustion was produced as the result of subject ing a partial combustion a mixture at said normally gaseous hydrocarbon and air of normal oxygen content. and thereafter passing the thus-produced gaseous mixture into contact with the iron catalyst to thereby convert said 3 gaseous product of partial combustion to synthesis gas consisting primarily of carbon monoxide and hydrogen.

2. The process of claim 1 in which steam is removed from the syntheses gas prior to its admixture with the combustion product.

3. The process of claim 2 in which the normally gaseous hydrocarbon is methane.

4. The process of claim 3 in which the volumetric speed of the mixture of methane and a gas selected from theg roup consisting of oxygen and oxygen-enriched air is 600.

5. The process of claim 1 in which the combustion takes place in the presence of a combustion catalyst.

6. The process of claim 5 in which the combustion catalyst comprises nickel.

7. The process of claim 6 in which the temperature of the combustion catalyst is 650-700 C. and the temperature of the iron catalyst is 740-760 C.

References Cited in the file of this patent UNITED STATES PATENTS 1,711,036 Beekly Apr. 30, 1929 2,529,630 Reichl Nov. 14, 1950 2,552,737 Rees May 12, 1951 2,558,760 Keith July 3, 1951 2,566,936 Garrison Sept. 4, 1951 2,605,174 Krejci July 29, 1952 2,631,086 Noak et a1 Mar. 20, 1953 2,681,272 Jewell June 15, 1954 2,683,12l Vincent July 6, 1954 2.683.152 Dickinson July 6, 1954 BEST AVAILABLE COPY UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,773,756 December 11, 19 76 Heinrich Merkel It .is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 15, for "to a" read --to the"; column 2, line 68, for a partial" read --to partial--.

Signed and sealed this 30th day of April 1957.

(SEAL) Attest:

KARL H. AJCLINE ROBERT C. WATSON Atte'st ng Officer Commissioner of Patents 

1. A CATALYTIC PROCESS FOR THE PRODUCTION OF SYNTHESIS GAS CONTAINING CARBON MONOXIDE AND HYDROGEN OF HIGH PURITY AND OF A RELATIVELY LOW NITROGEN CONTENT WITHOUT SUBSTANTIALLY IMPAIRING THE ACTIVITY OF AN IRON CONVERSION CATALYST EMPLOYED IN THE PROCESS, WHICH COMPRISES SUBJECTING TO PARTIAL COMBUSTION A MIXTURE OF A NORMALLY GASEOUS HYDROCARBON AND A GAS SELECTED FROM THE GROUP CONSISTING OF OXYGEN AND OXYGEN-ENRICHED AIR, THE OXYGEN BEING PRESENT IN AN AMOUNT INSUFFICIENT TO REACT COMPLETELY WITH SAID HYDROCARBON TO THEREBY FORM A GASEOUS PRODUCT OF PARTIAL COMBUSTION COMPRISING CARBON MONOXIDE, CARBON DIXOIDE, STEAM, AND UNREACHED NORMALY GASEOUS HYDROCARBON, ADMIXING SAID GASEOUS PRODUCT WITH AN AMOUNT OF SYNTHESIS GAS CONTAINING CARBON MONOXIDE AND HYDROGEN SUFFICIENT TO PRODUCE A GASEOUS MIXTURE IN WHICH THE PARTIAL PRESSURE OF THE STEAM AND THE PARTIAL PRESSURE OF THE CARBON DIOXIDE ARE REDUCED TO SUBSTANTIALLY THE VALVE WHICH WOULD BE OBTAINED IF THE GASEOUS PRODUCT OF PARTIAL COMBUSTION WAS PRODUCED AS THE RESULT OF SUBJECTING A PARTIAL COMBUSTION A MIXTURE OF SAID NORMALLY GASEOUS HYDROCARBON AND AIR OF NORMAL OXYGEN CONTENT, AND THEREAFTER PASSING THE THUS-PRODUCED GASEOUS MIXTURE INTO CONTACT WITH THE IRON CATALYST TO THEREBY CONVERT SAID GASEOUS PRODUCT OF PARTIAL COMBUSTION TO SYNTHESIS GAS CONSISTING PRIMARILY OF CARBON MONOXIDE AND HYDROGEN. 